| 摘要 |
PURPOSE:To enhance the reliability by incorporating a mechanism for deenergizing a motor upon heat generation, and by forcing the motor to be deenergized when the energization of the motor is continued for a predetermined time, irrespective of overheating of the motor. CONSTITUTION:A thermistor 40 which is located in the vicinity of a motor 22, is heated in accordance with a value of energizing current, or by external heat radiation so that opposite ends thereof are deenergized when the temperature thereof comes up to a predetermined value. The cathode side including two diodes 38, 42 is connected to one end of a capacitor 56 the other end of which is connected between resistors 52, 54. The capacitor 56 serves as a timer, and upon completion of charging of the capacitor 56, both ends of an ascending relay coil 36 and a descending relay coil 40 become the same potential, thereby magnetic excitation is removed. |
